The majority of electronic circuits, for which overheating is a risk, include a thermal protection device to prevent damage from excessive temperatures. When a first predetermined temperature is reached, this first temperature, of course, being less than an operating temperature that would risk damaging the corresponding circuit, the circuit is switched such that the output thereof is in the so-called “high impedance” state, also called “third state”. Such a state can be likened to an open circuit since, when this output is connected to a low impedance component, this component will not affect it. In this state, there is no longer any electric current flowing in the circuit and, therefore, the temperature of the circuit can decrease.
When the temperature of the circuit falls below a predetermined threshold corresponding to a second temperature, this second temperature being less than the first aforementioned temperature, the thermal protection can be stopped and the circuit is then switched for normal operation.
If the temperature increase which has caused the thermal protection process to start is due to a failure, this failure will reproduce a temperature increase in the circuit when the circuit is operated again if it is not eliminated. Therefore, this will repeatedly cause series of operational interruptions followed by restarting said circuit. These repeated cut-offs and starts can be damaging for the electronic circuit.
In particular, they cause accelerated degradation of said electronic circuit and, therefore, reduced reliability of the circuit.